Benzo-a-Pyrene: Environmental Partitioning and Human Exposure

A multimedia transport model was used to evaluate the environ mental partitioning of benzo-a-pyrene ( BaP) . Measured and pre dicted environmental concentrations were used to estimate the accumulation of BaP in the food chain and the subsequent ex tent of human exposure from inhalation and ingestion. Results show that BaP partitions mainly into soil ( 82%) and sediment ( 17%) and that the food chain is the dominant pathway of hu man exposure, accounting for about 97% of the total daily in take of BaP. Inhalation and consumption of contaminated water are only minor pathways of human exposure. The long-term av erage daily intake of BaP by the general population of the U. S. is estimated to be 2.2 micrograms (μ g) per day. Cigarette smok ing and indoor activities do not substantially increase human ex posure to BaP relative to exposures to background levels of BaP present in the environment. Since the increased lifetime risk as sociated with human exposure to background levels of BaP is 3.5 x 10 -4 , we conclude that ingestion of food items contami nated with BaP may pose a serious health threat to the U. S. population.